Abstract

Third-party cloud computing represents the promise of
outsourcing as applied to computation. Services, such as
Microsoft’s Azure and Amazon’s EC2, allow users to
instantiate virtual machines (VMs) on demand and thus purchase
precisely the capacity they require when they require it. In
turn, the use of virtualization allows third-party cloud
providers to maximize the utilization of their sunk capital
costs by multiplexing many customer VMs across a shared physical
infrastructure. However, in this paper, we show that this
approach can also introduce new vulnerabilities. Using the
Amazon EC2 service as a case study, we show that it is possible
to map the internal cloud infrastructure, identify where a
particular target VM is likely to reside, and then instantiate
new VMs until one is placed co-resident with the target. We
explore how such placement can then be used to mount cross-VM
side-channel attacks to extract information from a target VM on
the same machine.